I'm refinishing the white oak bright work on a 16' Classic Cat. The oak is slightly discolored in spots, mostly thin black stripping. I have been advised to use oxalic acid, but have some concerns.
The deck, hull and cockpit area are fiberglass, and the combing, rubrail and centerboard cover are white oak. I have been told that the acid will destroy the finish on the galvanized trailer and can discolor the fiberglass finish.
How do I treat the wood without affecting the fiberglass finish on the boat? How long can i leave the acid on the fiberglass without causing damage?
Any advice would be appreciated
Mask off the areas that the acid would damage with packing tape and poly sheets.
Mix about two tablespoons in a quart of hot tap water and allow it to dissolve. When dissolved, use an artist brush and paint it on the dark areas only. Allow to dry. The stain will lighten. If it does not disappear, then do another coat. You may need to coat it three or four times, allowing time to dry between coats. Once the stain is gone you can sometimes get a slight halo effect around the area where the stain was bleached.
To take care of this saturate a rag with the oxalic acid solution and wipe a thin coat over the stain and surrounding area. Allow to dry. This should take care of the stains. There is just one more step.
You need to neutralize the acid so it will not react with your final finish. Mix up two tablespoons of borax in a quart of hot water. Saturate a rag with the borax solution and wipe and allow to dry. Borax is sold in the super market laundry section as Twenty Mule Laundry booster. It is a natural product and also helps prevent rot.
